Here’s the half where he’s right: The President, as Commander-in-Chief, has the plenary power to direct the actual conduct of war on behalf of the United States. On that score, John and I are in full agreement. John Yoo is correct about the sweeping Commander-in-Chief power of the President to manage, direct, and command the actions of America’s armed forces, when lawfully deployed in the service of the nation.

But here’s the half where he’s wrong: The President does not have the plenary power to initiate war on behalf of the United States. For better or worse – I think for better, John thinks for worse – the Framers reserved that power to Congress. That’s where John Yoo and I part company.

There is a crucial difference between the Commander-in-Chief power of the President toconduct war and the explicit textual power of Congress to authorize war in the first place (whether done by formal declaration or by its legal equivalent). The Constitution draws a crisp distinction between these two distinct aspects of the war power. It assigns the power of war-initiation to Congress and not to the President. It assigns the power of war-execution to the President and not to Congress. (An important aside: The power to “declare war” does not require the use of magic words. Congress need not say the word “declare” and need not say the word “war” – and might well choose not to, for reasonable political or foreign policy reasons. Thus, Congress today typically “authorizes” the use of military force rather than formally declares war. But it is clear that, regardless of the form its enactment takes, the power Congress is exercising comes from the Declare War Clause.)

The division of the war powers is a near-perfect illustration of the framers’ obsession with separation of powers and checks-and-balances. Neither branch legitimately can usurp the primary war power of the other: the President may not assume to himself the power to declare war; Congress may not micro-manage the conduct of wars it authorizes. Each branch’s share of the war power acts as a strong functional check on the other’s actions. Constitutionally, neither branch can put us into a condition of war without the affirmative consent of the other.

John Yoo’s essay conflates these two distinct war powers. He draws on historical evidence concerning the President’s broad Commander-in-Chief powers as if it supported a plenary power of the President to start wars. In essence, Yoo argues that presidents have the power to initiate war because the framers understood the president to possess the exclusive power to conduct war. That is simply not logically sound.

The text, structure, logic, and original understanding of the Constitution are all on my side in this debate. That was the essence of my essay last week. It is a point I have made elsewhere on variousoccasions. As noted, John Yoo’s only contrary historical evidence concerns the president’s power to conduct wars, not to initiate them. (I will have more to say about this in a subsequent post.)

On the other hand, a good bit of modern practice – in conflict with the Constitution’s original allocation of powers – is on John Yoo’s side. In addition, there are decent policy arguments for vesting a war-starting power in the executive, rather than Congress – arguments that the framers considered and rejected.

So who wins? I have the text, structure, and historical evidence of original meaning. John has considerable contrary practice and good (if debatable) policy arguments.

Which view you think correct depends on whether you are committed to the original meaning of the Constitution or believe in a “living constitution” whose meaning shifts, evolves, or changes over time. Under the former view, the meaning of the Constitution is fixed at the time of its adoption, and established by the best evidence of original meaning. Under the latter view, practice departing from original understanding can change – or simply define – the meaning of the Constitution. Moreover, as we learn from experience, and as we consider changed circumstances and new policy wisdom, the Constitution can and should adapt to such new insights, producing new understandings.

The difference between Yoo and me thus turns almost entirely on constitutional interpretive methodology. I am a pure-as-they-come, original-public-meaning textualist. (Or so I like to think.) The meaning of the Constitution is determined by, and only by, the original meaning its words and phrases would have had, in political and linguistic context, to reasonably informed speakers and readers of the English language at the time they were adopted. What counts are the words of the document, the logic of its structure, and historical evidence of its original public meaning. What does not count is practice, precedent, or policy at variance with the Constitution’s actual meaning.

John Yoo is to some extent – on war powers at least – a “living constitutionalist.” What counts most heavily is what works, what seems most sensible from a policy standpoint (at least in the eyes of some), and the evolving pattern formed by established practiceand precedent.

Now, this is not an entirely crazy position. Many legal scholars hold it in various forms. But it is typically a methodology associated with “judicial activists.” (Interestingly, this is not so with respect to war powers, an area where most on the Legal Left become transformed into devotees of a strict original-meaning reading of the text – a point of irony to which I will return.) But this should bother John Yoo, who is usually “originalist” in his methodology. Calling him a “living constitutionalist” is something of an insult in our common legal circles. (Sorry, John!)

Am I wrong about this? Is not the whole burden of John Yoo’s essay that the proper meaning of the Constitution, on the question of who gets to start wars on behalf of the United States, is determined by practice and policy? Is not the only evidence he draws from original-era historical sources directed at the president’s powers of war-execution and not war-initiation?